Open coil heating element assembly

ABSTRACT

An arrangement for supporting open coil heater elements including a baseplate and a pair of spaced arms projecting from the plate. Each arm is rigidly affixed to the baseplate at one of its ends. A plurality of spaced cross supports are attached to the arms. The cross supports comprise plates having apertures therein to receive insulators through which the heater elements pass. The ends of the heater elements are appropriately connected to circuit terminals mounted to the baseplate.

United States Patent Ammerman et al.

[ Feb. 8, 1972 [54] OPEN COIL HEATING ELEMENT ASSEMBLY [72] Inventors:George Edward Ammerman; William Mc- Farlane, both of Murfreesboro, Tenn.

[52] US. CL ..219/532, 219/536, 219/546, 338/299, 338/317 [51] Int. Cl...H05b 3/06 [58] Field ofSearch... ..2l9/532,536-537, 219/539, 550, 546;338/299, 317-321; 174/1 1,813,767 7/1931 Reichart ..219/536 1,911,3835/1933 Noble ..219/532 2,130,600 11/1939 Mills ..219/532 3,213,40110/1965 Owen ..219/539 X FOREIGN PATENTS OR APPLICATIONS 506,072 9/ 1930Germany ..219/532 Primary Examiner-Volodymyr Y. MayewskyAttorneyCushman, Darby & Cushman 57 ABSTRACT An arrangement forsupporting open coil heater elements including a baseplate and a pair ofspaced arms projecting from the plate. Each arm is rigidly affixed tothe baseplate at one of its ends. A plurality of spaced cross supportsare attached to [56] References Cited the arms. The cross supportscomprise plates having apertures UNITED STATES PATENTS therein toreceive insulators through which the heater elements pass, The ends ofthe heater elements are appropriately 1 RlCe connected to circuitteminals mounted to the basep|ate 1,597,304 8/1926 Warner et al...2l9/532 X 3,016,441 l/1962 l-lackman et a1 ..2l9/532 2 Claims, 5Drawing Figures I l J PAIENTEDFEB 8 I972 3.641.312

INVENTORS F7 5 420262- Jim 4,817 QMMIIPAIfl/V ATTORNEYS OPEN COILHEATING ELEMENT ASSEMBLY This invention generally relates to an improvedconstruction for supporting a plurality of conventional open coilheating elements and, more particularly, to structure wherein theheating elements are stacked in spaced parallel planes. Such arrangementof heating elements finds application in the heating andair-conditioning field. For example the invention is useful as a heaterwithin ductwork, in combined heating and cooling air conditioners, inassociation with fan coil units, in heat pumps, etc.

In the past heating elements in plural planes have been supported byseparate frames or single ones having such complexity as to make themquite expensive. The present support arrangement incorporates a reducednumber of components which produces economical advantages for theassembly, and which causes only low impedance to airflow past theheating elements. The assembly further provides a baffling capability toimprove the operating characteristics of temperature sensors which areutilized in conjunction with the heating elements.

Briefly, the invention comprises a baseplate and a pair of spaced armsprojecting from the plate. Each arm is attached at one of its ends tothe baseplate. A plurality of spaced cross supports extend between thearms and are rigidly affixed thereto. The cross supports comprise plateshaving apertures therein arranged with their centers aligned in spacedparallel planes. The apertures receive insulators through which heatingelements pass. By the arrangement just described, a plurality of opencoil heating elements are supported in parallel planes by a singleframe. The cross support plates can be attached to the arms at differentangles to thereby deflect air flowing past the heaters causing abaffling effect.

The invention will be described in further detail by reference to theaccompanying drawings, wherein:

FIG. 1 is an illustration of an open coil heating element assembly in atypical operative position with respect to an air duct and blowerarrangement;

FIG. 2 is an elevational view of an open coil heating element assemblymade in accordance with the invention;

FIG. 3 is an elevational view of the assembly taken at 90 to that viewshown in FIG. 2;

FIG. 4 is an enlarged detail view of the mounting arrangement for aninsulator through which a heating element passes; and

FIG. 5 is a view in section taken along line 5-5 of FIG. 4.

Referring now to the drawings, a preferred embodiment of the inventionwill be described in detail. The description will be of an open coilheating element assembly used to warm air passing through a duct.However, it will be understood, as hereinbefore stated, that the heatingelement assembly may be employed in a number of other environments. InFIG. 1, the duct is indicated by the numeral 10, and a conventionalblower 12 is employed to force air through the duct. The open coilheating element assembly 14 is arranged to project into the air flowpath such that the major plane of each open coil is substantially normalto the air flow. The heater coils are connected to an external voltagesource (not shown) for energizing the coil.

The details of the heating element assembly can be appreciated byreference to FIGS. 2 and 3. More particularly, the assembly comprises abase member comprising plate 16 from which a pair of spaced arms 18 and20 project normally to the plane of the baseplate. Arms 18 and 20 arerigidly fastened to the plate 16, typically by welding a foot 22 at theend of each arm to the baseplate.

A plurality of spaced cross support elements 24 extend between arms 18and 20. As can be seen in FIG. 3, elements 24 are positioned on oppositesides of The arms 18 and 20. The elements 24 are plates having footportions 25 which are secured to the arms 18 and 20 by a suitable meanssuch as by spot welding or riveting. Accordingly, the baseplate l6, arms18 and 20, and cross support elements 24 are rigidly joined together.

Each of the cross support elements 24 is provided with a plurality ofspaced apertures 26 (FIGS. 4 and 5). The apertures are arranged withtheir centers aligned in spaced parallel planes (FIG. 3). Within asingle plane the apertures of adjacent elements 24 are aligned in amanner to receive a single open coil heating element as will now bedescribed.

The walls of each aperture 26 are pierced radially as at 28 (FIG. 4) toform tongues 30. Adjacent tongues 30 are inclined outwardly in oppositedirections from the plane of the plate 24. By such an arrangement, thesetongues serve to support cylindrical ceramic heating coil insulators 32each having a projecting rib 34 about its periphery. The insulatorconstruction and the manner by which it is held within an aperture 26can be appreciated by reference to FIG. 5. Heating coils 36 projectthrough the insulators in aligned apertures in a serpentine manner as iswell known in the art. Such an arrangement is shown in FIG. 2. The endsof each coil are connected to a power source (not shown). Typically, oneend 38 of the coil passes through an insulator 40 attached to baseplatel6 and is provided with a terminal 42 on the opposite side of thebaseplate from the coil (FIG. 2). The other end of the coil is joined toa screw-type terminal 44 joined to an insulator 32 within an aperture 26in a cross support plate 24 adjacent the baseplate. A fuse 46 ispositioned between terminal 44 and an external terminal 48 supported bya further insulator 50 projecting through the baseplate 16. When poweris applied at terminals 42 and 48, the respective open coil heatingelement is energized so as to warm air passing normal to the plane ofthe coil.

In the embodiment shown in FIGS. 2 and 3, a single open coil heatingelement is associated with one set of cross supports 24, and a pair ofopen coil heafing elements is illustrated as being supported by thesecond set of cross supports 24. However, by enlarging the platescomprising cross supports 24 and by providing suitable rows of apertures26 therein, further open coil heating elements can be stacked inparallel-spaced relationship with the coils shown without therequirement of additional frame members. Thus, it can be appreciatedthat in accordance with the present invention a number of parallelspacedcircuits may be supported by each cross support 24. This constructionpermits substantial economy in construction.

When assembly 14 is in its operative position within a duct, it isdesirable that the side of the frame opposite that attached to thebaseplate 16 be secured to the opposite side of the duct. This can beaccomplished by one of the arms 18 being made longer than the other soas to project through an aperture in the wall of the duct to therebysupport the end of the heating element assembly remote from baseplate16.

When installed within a duct, the heating element assembly is insertedthrough an aperture in the wall of the duct and the baseplate 16 issecured to the wall adjacent this opening. The end of the assemblyremote from plate 16 is secured to the opposite duct wall as has justbeen described. By connecting the plurality of open coil heaters torespective power sources, the heaters are energized.

Typically, an aperture is provided in the baseplate 16 to permit sensorsto project into the area of each of the open coil heaters. These sensors(not shown) operate to control the application of power to therespective heater. Ideally, the sensors are responsive to thetemperature of the air passing through the duct, but in practice, theyalso respond to radiant heat 1 generated by the heaters. It has alsobeen found that there is a tendency for air along the walls of the ductto stagnate, and this also introduces problems of controlling theoperation of the sensors to achieve the desired air temperature withinthe duct. The present structure assists in reducing the problems ofsensor control. More particularly, the cross support elements 24 may bevaried so that the feet 25 meet the main plate portions of therespective elements 24 at angles other than When this is the case, theplate portions of the support elements serve as a bafi'le to divert theair flow from its normal path past the heater coils. By proper selectionof the angle between feet 25 and the main plate portions of supporteleits ends to said base member and projecting normally ments 24, airmay be directed to downstream sensors so as to therefrom; cool them toreduce the radiant heat effect and also to assist a plurality of spacedcross support elements, said cross supin maintaining the flow of air atthe walls of the duct commenport elements comprising flat, oneplaneplates extending surate with the main air flow. This permits the sensorsto more 5 t n a d arm a d rigidly j ined th ret and araccurately monitorthe true air temperature within the duct. r ng in pl nes substantiallyparallel to the plane of said The structure disclosed her in i anexample f an arrangebase member, each plate having at least two rows ofa plument in which the inventive features of this disclosure may be ofapertures therein, the 0f the p r e utilized, and it will becomeapparent to one skilled in the art beilfg aligned l spaced P P and eachaperture that certain modifications may be made within the spirit of the"}"8 a P of tongues radially arranged about its invention as defined bythe appended claims. P p y and w is claimedis; insulators supported bysaid tongues within said apertures,

said heating elements passing through said insulators. 2. An assembly asset forth in claim 1 wherein the planes of said cross support elementplates are variable.

1. An assembly for supporting a plurality of open coil heating elementsin spaced parallel relationship, including:

a base member;

a pair of spaced parallel arms each rigidly attached at one of

1. An assembly for supporting a plurality of open coil heating elementsin spaced parallel relationship, including: a base member; a pair ofspaced parallel arms each rigidly attached at one of its ends to saidbase member and projecting normally therefrom; a plurality of spacedcross support elements, said cross support elements comprising flat,one-plane plates extending between said arms and rigidly joined theretoand arranged in planes substantially parallel to the plane of said basemember, each plate having at least two rows of a plurality of aperturestherein, the centers of the apertures being aligned in spaced parallelplanes and each aperture having a plurality of tongues radially arrangedabout its periphery; and insulators supported by said tongues withinsaid apertures, said heating elements passing through said insulators.2. An assembly as set forth in claim 1 wherein the planes of said crosssupport element plates are variable.